Why my php substr() shows obscure characters when cutting a text?

Question

I\'m using the substr() function to limit the characters in strings. but sometimes, the output text contains some obscure characters and Question marks etc...

Answer 1

Just to extend the Gurmbo is answer. Using mb_substr will solve your problem but still if special characters comes at the end when you trip, it still shows the some special characters. So when I did some research, wordpress having method wp_html_excerpt to solve this problem.

wp_html_excerpt method removes those special characters from the end of line.

Here is the source code from wordpress.

/**
 * Safely extracts not more than the first $count characters from html string.
 *
 * UTF-8, tags and entities safe prefix extraction. Entities inside will *NOT*
 * be counted as one character. For example & will be counted as 4, < as
 * 3, etc.
 *
 * @since 2.5.0
 *
 * @param string $str   String to get the excerpt from.
 * @param int    $count Maximum number of characters to take.
 * @param string $more  Optional. What to append if $str needs to be trimmed. Defaults to empty string.
 * @return string The excerpt.
 */
function wp_html_excerpt( $str, $count, $more = null ) {
    if ( null === $more )
        $more = '';
    $str = wp_strip_all_tags( $str, true );
    $excerpt = mb_substr( $str, 0, $count );
    // remove part of an entity at the end
    $excerpt = preg_replace( '/&[^;\s]{0,6}$/', '', $excerpt );
    if ( $str != $excerpt )
        $excerpt = trim( $excerpt ) . $more;
    return $excerpt;
}